Electric heater



'Fehi 1928.V

1,659,400 J. M. FRANK ELECTRIC HEATER Filed Jan. 2l 1924 IN VEN TOR.Jaim iEzm/Q ATTORNEY es@ i4, leas. lalflll@ SA'ES ENT Application iledJanuary fl, 19%. Serial No. 687,436.

rihis invention relates to electric heating devices of the typeconnnenly hnovvn as grid heaters and which, generally described,coinprise a grid-lille structure or a group ot such structures bondedtogether and heated by the 'passage oi' a current et' electricitythrough the resistance parts or elements et' the grid or grids.

ln designing my present heater i have chiedy in mind its adaptabilityand nt heating` a current air llon'ing thi the grid. rlhere are a numberot sitaacions Where a heater ot this character may be usefully employed,For instance, in a co-pending application ior a heating and Ventilatingapparatus, Serial No. 682,163, tiled December 22, 1923, l have disclosedthe use ot an electric heater for Warming a current ot air induced orpropelled into a room by a tan; the air current being caused to travelacross and through the electric heatingl element.

tailed description, taken in connection with the accompanying drawing inwhich l have illustrated one practical form ot' the invention, andwhereinelectric heater grid, showing duplicate upper and lower sectionsfor the sake or' increased capacity, but either section alone enibod.yin,l the broad principle of t-he invention;

Fig. 2 is a top plan view ot a, ,group or stack ot grids such as isshown in Fig. l in assembled relation; and

3 is an enlarged cross-section through one oit the intermediate limbsor" the grid.

Referring to the drawings, and iirstdescribing the unitary gridstructure, this comprises parallel spaced bars 5 that constitute theside trame limbs or" the grid, and an intermediate group ot narrowerparallel limbs 6 lying in the plane ot the bars 5 and integrallyconnected to each other at their oppoh( ilit i Where a heater is used inthis Yay. it is desite ends by curved portions G ci the same sirablethat the heater itselt shall be so decross-section as the limbs 6. Thegreater signed as not only to possess as large a racross-section ot theside trame limbs 5 is to diatling capacity as possible, but also tootter the minimum resistance or obstruction to the lion7 of the air; andto provide a heater et such a design has been one oi the objects ot thepresent invention. @ther more specilic objects are, to provide a heateroit very simple, rugged and economical construction; to provide a heateraiiiording a large area radiating surface in -relation to its size andits capacity to readily permitI the tloiv et air therethrough, toprovide a heating` grid having limbs Which shall possess an oval orsulstantially stream-line form in cross-section in a. directiontransverse to the plane oit the grid and having such limbs equipped withheat-radiating tins also so termed and arranged as to otter a minimumresistance to the tlow ot air; and to provide a heating grid of such astructure that duplicate units thereof may readily be assembled on acoinmon. support` in such a manner that corre spending limbsotvlaterally adjacent `grids will be relatively staggered or offset. sothat the air flowing through the stack ot grids thus assembled will haveto Jlolloxv serpentine path. thereby picking` up a maximumA amount orheat during such 'llont ther objects and attendant advn the inventionWill be apparent to i skilled in the art as the same becoin understoodby reference to the tolloi aliiord mechanical strength; and the outerlimbs 6 are integrally oined to the limbs 5 by curved portions 5, thustorming a continuous zigzag structure. As shown in 2 and especially inthe sectional view 7Eig. 3, the limbs of the grid are generally oval orstream-line 'form in cross-section, with the maior axis of the ovaltransverse and preterably normal to the plane ot the grid. To increasethe heating capacity et the grid the limbs t-hereoiC are equipped atspaced intervals with radial line 7 on their adjacent sides, these iinsbeing crescent shaped and Widest at their central portions and graduallynarrowing and merging into the body oi the limb at the ends ot the maioraxis oi the latter. It Will also be observed that the tins on adjacentlimbs are relatively offset or staggered. llhen made in this form. andso arranged, the tins 7 substantially increase the heating surface andcapacity while offering but very slight additional frictional resistanceto the passage of the air.

On the free ends ot' the outer limbs 5 ot the grid are termed aperturedhubs S; and Where the grid is made double, that is, with like upper andlower relatively inverted Sections, as shown in Fig. l, the hubs 8 aremade common to the corresponding` limbs 5 ot both sections, being'located at the juncture of' said limbs and serving to integrally connectthem.

A es ot ersons better Fig. l isa side elevation of my improved (iii a, ll

Where ai heater isl composed of aplurality of grids, these may beassembled side by side and connected by through blots 9 extendingthrough the several hubs 8, with suitable sleeve insulation 10 betweenthe bolts and the hubs. '-11 designate a pair ot tie plates throughwhichthe'bolts 9 also pass, and 12 are nuts on the projecting ends of thebolts 9' for bonding the structure together. The tie plates 11 may alsoserve in part as a means for supporting the grid on, or attaching to,the sti'ucture it is designed to serve.

V13 designate metallic washers, and 14 insulating washers, so disposedon `the bolts 9 and between the hubs ot the `several grid Vsections asto insure a zigzagrflow ot the current from one grid to and throughthe.y

in JFig. 2 I have shown the current entering by a circuit wire 15 to oneof the metallic washers'13j at the left of the front of the grid, whencethe current flows through the front grid thence crosses through themetallic washer 13 atV the other side tothe second grid, allowing backthrough thev latter. thencethrough the second metallic washer at theleft to and through the third grid, and thence through the metallicwasher at the rear on the right hand side and out'through the circuit`line 16.` Now by reference .to Fig. 2 it will be observed Vthat thelimbs 6 ot each grid lie directly in iront ot or behind therspacesbetween the similar limbs of the next adjacent grid. By reason ot thisarrangement, in a'multiple grid heater, a current of air flowing throughthe grid necessarily follows a more or less serpentine path, as shown bythe arrows in F ig. 2, whereby it is caused to come into most intimatecontact with each section of the heater thereby picking up the maximumamount oi ieat from the latter. This alternate or staggered arrangementis very simply and economically effected, from a'manutactui'ingstandpoint, by so building each grid that, while the several limbs 6 areequally spaced from each other, the outer limbl 6 on one side is nearerto its adjacent supporting limb 5 than is the corresponding outer limb 6on' the opposite side to its adjacent supporting limb 5. The result isthat the grids may all be made exactly alike; and, to obtain thestaggered or offset grouping hereinabove described, it is necessary onlyto relatively side-V wise invert adjacent grids ot theA group Byreasonof the described structure the frictional and other resistance oiieredto the passage ot an air current through the heater is reducedto aminimum.'

succeeding grids of the series. For instance.

'VVliile I have described my invention mainly designed for the heatingof a current ofair drawn or propelled therethrough, and

contemplate 'tliatsuch will be its` principal application and use, yet ldo not wish to be understood as limiting the invention to an electricheater tor warming a current of air Vflowing therethrough, since thedescribed structure or' grid, and the multiple grouping or arrangementthereof herein shown,-may manifestly be used to advantage iii othersituations and relations where an electric heater is desired orrequired.

1I claim- Y f l. An electric heateir'grid, including a plurality ctspaced parallel limbs located in a common plane and provided with radialtins on their adjacent sides, the tins on adjacent limbs beingrelatively oii'set or staggered.

2. Anr electiicgiid, including Va plurality oi'spaced parallel limbslocated in a common plane and oft a generally oval'torm in crosssectionwith the major axis of the oval transverse to said plane; said limbsbeing provided with radial ifins of crescent shape on their adjacentsides.

8. Anelectric grid, including a plurality oi spaced parallel limbslocated in a common plane and` of stream-line Vfor-min cross-sectionwith their major transverse vaires normal to said plane; said` limbsbeing provided with radial' iins of crescent shape on their adjacentsides, and the iins on adjacent limbs being relatively otfset orstaggered.

e: An electric heater, comprising a `plurality ot grids each formed withVspaced parallel limbs disposed in a common plane,

means for uniting said grids in side-by-side relation, the limbs ofadjacent grids, when the latter are united, being relatively offsetlaterally, and means for passing d current through said grids insuccession.

5. An electric heater, consisting ot a group of duplicate gridsdisposedV side by side land each comprising a pair of spaced side tramelimbs formedV with apertured hubs and a group of intermediate parallellimbs located between and in the plane ot said side trame limbs andlengthwise continuous with the latter and with each other, the outermostlimbs of said intermediate groupbeing ditferentially spaced from theiradjacent side frame'liinbs and adjacent grids being relatively invertedsidewise whereby their'inter mediate limbs are relatively oii'set orstaggered laterally, insulated tie-bolts passed through the hubs of the`grids and bonding the latter together, and alternately arranged conducting'and insulatingwashers onsaid tie-bolts between adjacent hubs,whereby current is passed through said grids in succession from one sideof the group to the other.

Jointv M; risalita.V

